Heavy gunfire could be heard Sunday in the Syrian city of Homs, according to an opposition activist group.

Syrian security forces were involved in heavy shooting using machine guns and tank mortars, the Local Coordination Committees said in a statement.

In the neighborhood of Bab Sbaa, explosions were heard and electricity was cut off on several streets, according to the group.

Also Sunday, employees of the Agriculture Department in Homs were attacked and injured by an "armed terrorist group," according to the official Syrian Arab News Agency.

The London-based Syrian Observatory for Human Rights said the deputy director of agriculture in Homs survived an assassination attempt when unknown gunmen fired shots at his car.

Another opposition group, the Revolutionary Council of Homs, said that the western Syrian city remains isolated, with all major roads cut off. The group also said landline phones and the internet were not working in several Homs neighborhoods.

"It's like a war zone," a Homs resident and opposition member told CNN. This man is not being named by CNN for security reasons.

He said he can see at least eight tanks within a few hundred meters of his home, and that the constant gunfire he's heard since Friday increased in intensity Sunday during the early evening hours.

"I believe this nation wants the regime to fall," el-Arabi said. "And I know that we will pay a heavy price, but I want the international community to help reduce that price."

CNN is unable to independently confirm death tolls or events in Syria, which has restricted access to many parts of the country by international journalists.

Meantime, embattled Syrian President Bashar al-Assad and Foreign Minister Walid al-Moallem had harsh words for nations that appeared unsympathetic to their government.

"Syria will take strong measures against any country that recognizes the opposition council formed in Turkey," al-Moallem said, referring to a new alignment of Syrian opposition groups, the Syrian National Council, which announced last week in Istanbul that it will "represent the Syrian revolution."

"I am not interested in what they seek," he said, according to the official Syrian Arab News Agency (SANA).

"Do the armed terrorist groups want to hold a national dialogue? ... Do the armed groups, which assassinate intellectuals and scholars, want reforms in Syria?" he asked. "These groups kill people for money; therefore I don't see any relation between what they do and the reform program and the scheduled dialogue."

Al-Moallem was speaking to delegates from the eight-member Bolivarian Alliance for the Americas, who were in Damascus to show their support for al-Assad.

The president also met with delegates, stressing that the reform process in Syria will move forward "independent of any foreign dictates," SANA reported.

"The foreign attack on Syria got more fierce as soon as the internal situation started to get better, since what they want is not reforms, but to make Syria pay the price for its stances and defiance of the foreign plots in the region," al-Assad said.

Al-Moallem also warned countries to protect Syrian embassies on their soil, after protesters attacked Syrian embassies in Berlin, London and Vienna over the weekend.

"I warn the countries who do not protect the Syrian missions in their countries, we will treat theirs equally in Damascus," Syria's foreign minister said Sunday.

Two dozen people stormed the Syrian embassy in Berlin on Saturday night and caused extensive damage inside the building, police in that city said. Officers were dispatched to the scene and spoke to the activists, who then relented and left the embassy. There were no arrests.

That incident came after an attack the night before on the Syrian's embassy in Vienna, in neighboring Austria.

About 20 people entered the second floor of the embassy and caused damage on the premises, police spokesman Hannes Hartl told CNN Sunday.

More than 10 people -- all Syrian nationals living in Austria -- were held in custody until the following day, he said.

And at least five people were arrested Saturday afternoon outside the Syrian Embassy in London, suspected of criminal damage, the Metropolitan Police said.

"Three people involved in protests outside the Syrian embassy in London gained access to the roof of the entrance of the embassy. They were taken down and arrested," the police said in a statement.

"There was no breach of security, and they never gained entrance to the embassy. The other two were arrested after that for separate incidents relating to the protests outside the embassy," they said.

Protests in Syria erupted seven months ago, and demonstrators want a Syria free of the Assad regime as well as democratic elections, they say. Assad has been in power since 2000; his father, Hafez, ruled Syria for three decades until his death that year.

The United Nations estimates that more than 2,900 people have died since the uprising began in mid-March.

Opposition activists say the government crackdown is a systematic, sustained slaughter.